This is a Phase 1, open label, dose escalation, multi-center clinical trial of Allogeneic
Bone Marrow-Derived Human Mesenchymal Stem Cells (hMSCs) for the treatment of Acute
Respiratory Distress Syndrome (ARDS). The purpose of this study is to assess the safety of
hMSCs in patients with ARDS.

The primary objective of this study is to assess the safety of intravenous infusion of
Allogeneic Bone Marrow-Derived Human Mesenchymal Stem Cells (hMSCs) in patients with ARDS.

Inclusion Criteria:

Patients will be eligible for inclusion if they meet all of the below criteria. Criteria
1-3 must all be present within a 24-hour time period and at the time of enrollment:

Acute onset (defined below) of:

1. A need for positive pressure ventilation by an endotracheal or tracheal tube with a
PaO2/FiO2 ratio < 200 with at least 8 cm H2O positive end-expiratory airway pressure
(PEEP)

3. No clinical evidence of left atrial hypertension for bilateral pulmonary infiltrates.

In addition to meeting inclusion criteria, enrollment must occur within 96-hours of first
meeting ARDS criteria per the Berlin definition of ARDS.

Exclusion Criteria:

1. Age less than 18 years

2. Greater than 96 hours since first meeting ARDS criteria per the Berlin definition of
ARDS

3. Pregnant or breast-feeding

4. Prisoner

5. Presence of any active malignancy (other than non-melanoma skin cancer) that required
treatment within the last 2 years

6. Any other irreversible disease or condition for which 6-month mortality is estimated
to be greater than 50%

7. Moderate to severe liver failure (Childs-Pugh Score > 12)

8. Severe chronic respiratory disease with a PaCO2 > 50 mm Hg or the use of home oxygen

9. Patient, surrogate, or physician not committed to full support (exception: a patient
will not be excluded if he/she would receive all supportive care except for attempts
at resuscitation from cardiac arrest).